Over 3000 children died in residential schools in Canada, although the number is likely much higher because deaths were not properly recorded. Diseases often spread through the school and some students who were abused committed suicide. The bodies of students were often buried in unmarked graves.
Source: National Post. “Attitudes of ‘coldness, indifference’ behind thousands of residential school deaths:TRC report.” December 15, 2015. https://nationalpost.com/news/canada/attitudes-of-coldness-indifference-behind-thousands-of-residential-school-deaths-trc-report